Amphibians are used extensively as scientific model organisms, in health and environmental research, as test organisms, and have an undeniable role as sentinel species, as a food source, and in insect control. In contrast to mammals with extensive genomic resources, a particular challenge exists for evaluating gene expression endpoints in amphibian species where clades exhibit evolutionary divergence of over 300 million years (AmphibiaWeb 2012). Of the amphibians, the Anura-representing frogs and toads are the most numerous on the planet representing over 6,000 of the ˜7,000 known species (AmphibiaWeb 2012). Despite this impressive number, only two closely-related Pipid species, Xenopus laevis and Xenopus tropicalis, have sufficient genomic resources for gene expression studies. Yet many other species including ones that have diverged over 200+ million years ago, serve as important species, regionally and globally. There is a lack of the most minimal genomic information leading to a significant investment in time and resources to even clone a portion of a single gene in order to develop validated gene expression tools for a species of interest. To circumvent this difficulty, we have developed a suite of qPCR-ready primer sets that identify particular genes and/or their transcripts. Each primer pair has been validated to function under stringent criteria in species as diverse as Pipids and Ranids. The use of these primer sets provides a simple, low-cost solution to the issue of cross-species comparison of responses and sensitivities.
Endocrine disruptors (EDCs) are chemicals, either environmental or man-made, that disturb the endocrine signaling pathways of humans and wildlife. EDC exposure often results in cancer, fertility problems, and other diseases (Vandenberg, Colborn et al. 2012). Therefore, the risk from these exposure effects has led to a great need for sensitive and appropriate methods for indicating deleterious EDC effects. For this reason, there is considerable interest in developing novel diagnostic assays to detect EDCs in the environment as well as in products meant for human consumption or that are used to package food products such as plastic food containers. Over 80,000 chemicals are registered for use in the US (NIEHS 2013) and there is increasing concern regarding their impact since it is now established that EDCs do not follow the classical rule of “the dose makes the poison” (Vandenberg, Colborn et al. 2012). Rather non-monotonic responses and low-dose effects are actually common in studies of natural hormones and EDCs and clear linkages between environmental exposures to EDCs and human diseases/disabilities are becoming evident (Vandenberg, Colborn et al. 2012). EDCs are generally found in low concentrations in the environment, but even minute quantities can have demonstrable impact as hormone disruptors. In fact biological activity can be detected below current analytical detection limits and measurement of EDCs in the context of complex mixtures such as municipal wastewater effluent is not necessarily a good predictor of biological activity (Quanrud and Propper 2010). Given that many aquatic ecosystems contain significant concentrations of environmental contaminants (Kolpin, Furlong et al. 2002), and that many of these compounds and/or their metabolites have been detected in human plasma (National Report on Human Exposure to Environmental Chemicals, Centers for Disease Control and Prevention, U.S. Department of Health and Human Services, http://www.cdc.gov/exposurereport), we have developed a suite of tools for indicating deleterious EDC effects. Such screens can be used as a first level evaluation of exposure health risk for both wildlife species and humans. Most of what we know about EDCs pertains to substances that disrupt estrogen signaling pathways and technologies to detect estrogenic EDCs have been developed (Van Aggelen, Ankley et al. 2010; Hecker and Hollert 2011).